1. Field of the Invention
The present invention relates to a circuit board, and, particularly, to a circuit board for LED (light emitting diode).
2. Description of the Prior Art
The LED package mainly includes processes such as chip mounting, wire bonding, glue molding, cutting, test, and packing. The LED is allowed to be integrated with other electric circuit, as well as supported and protected.
In the chip mounting process, the LED will be fixed on the circuit board. Generally, an insulating adhesive is used for bonding the LED, as shown in FIG. 1. FIG. 1 shows a wiring diagram of a conventional circuit board for LED. Referring to FIG. 1, a circuit board 10 for LED has a chip mounting area 11 and a wire bonding area 13. The chip mounting area 11 is coated with an insulating adhesive to bond an LED 15 onto the chip mounting area 11. Thereafter, one electrode of the LED is electrically connected with the wire bonding area through a wire by bonding. However, the adhesive tends to flow along the shape of the wire bonding area and to the location for bonding the wire on the wire bonding area, due to the low viscosity of the adhesive. As a result, the wire can not electrically connect the electrode of the LED and the wire bonding area 13 having the insulating adhesive thereon according to a predetermined design. Such situation will lead to a poor reliability for the packaging process.
FIG. 2 shows a wiring diagram of another conventional circuit board for LED. Referring to FIG. 2, the circuit board 20 for LED has a chip mounting area 21, wire bonding areas 22 and 23, and four through holes 26, 27, 28, and 29. An LED 25 is electrically connected by bonding to the wire bonding areas 22 and 23 through a wire. The wire bonding area 22 connects the through holes 26 and 27 and the wire bonding area 23 connects the through holes 28 and 29, to allow two electrodes of the LED 25 to be electrically connected with the internal circuit of the circuit board 20. However, with such wiring scheme, the through holes occupy most area of the circuit board 20, and accordingly the amount of the LEDs 25 mounted on the circuit board 20 is limited.
Therefore, an improved circuit board for LED is needed to solve the aforesaid problems, such as adhesive overflow and excessive area occupied by the through holes on the circuit board for LED.